This study is designed to (a) establish the factors involved in the induction and release of two neutral proteases, collagenase and elastase, from resident lung macrophages and their precursors, circulating monocytes; and (b) to determine the capabilities of various drugs which may modulate the production of collagenase and elastase. Rabbit, guinea-pig or human alveolar macrophages and circulating blood monocytes will be used in this study. These cells will be maintained in tissue culture and the induction and release of collagenase, elastase, lysozyme and beta-glucuronidase will be studied. Biochemical characterization of AM collagenase and elastase will also be attempted. The effect of phagocytosis, cigarette smoke extract, corticosteroids and other non-steroidal anti-inflammatory drugs on induction and release of the above mentioned enzymes will be investigated. Specific comparisons between the secretion rates of both collagenase and elastase by human alveolar macrophages obtained by bronchoscopy from smokers and non-smoker volunteers will also be studied. All of the enzymes will be measured colorimetrically using native substrates. BIBLIOGRAPHIC REFERENCES: Gee, J.B.L. and Khandwala, A.S.: Oxygen metabolism in the alveolar macrophage: Friend or foe? J. Reticuloendoth. Soc. 19: 229, 1976. Gee, J.B.L. and Khandwala, A.S.: Oxidants and phagocytosis. Lung Cells in Disease (ed.) A. Bouhuys, North-Holland Publ. Co., Amsterdam, 1976, p. 181-182.